The use of tooth positioning and retaining appliances in the orthodontic treatment of patients is well known. Such appliances are both custom made and preformed. An apparatus and method for making custom appliances is disclosed in U.S. Pat. No. 2,775,036. Preformed appliances are disclosed in U.S. Pat. Nos. 3,724,075 and 3,837,081. The latter two patents also make it well known to use a resilient thermoplastic material for making such appliances. Such material having the capability of being optically clear has also been known. It is also well known to mold air holes or airways in such appliances, as disclosed in U.S. Pat. No. 4,195,046.
Both U.S. Pat. Nos. 2,775,036 and 4,195,046 teach the method and apparatus for making custom tooth positioning and retaining appliances where a three-part dental flask is employed, the central part of which coacts with upper and lower parts. The central part receives a blank of moldable material which upon being heated and being subjected to mold members mounted in the upper and lower parts becomes a custom-molded appliance. Following the removal of the molded appliance from the flask, it must be trimmed and/or buff polished before it is ready to be used by a patient.
Custom-made resilient plastic appliances have been available with shiny surfaces, but such appliances are not optically clear. It has also been known to provide preformed appliances molded of resilient thermoplastic material that are substantially optically clear, but those appliances are never subjected to trimming and/or buff polishing.
Heretofore, it has also been known to make custom appliances from a thermosetting resilient material such as rubber and other thermosetting plastics, however, none of which are optically clear after being trimmed and/or buffed. Mainly for aesthetic reasons, certain orthodontists prefer to use for their patients what has been heretofore defined as a transparent appliance made generally by a thermoplastic material, but which is semi-opaque or frosty in appearance and actually translucent. Accordingly, it has not been possible to heretofore provide the custom-made appliance that has been subjected to trimming and/or buff polishing to be truly transparent or optically clear. Thus, such a preferred appliance, long desired by orthodontists has not been available.